Centred butterfly valve

Abstract

Valve comprising a body (2), a centred butterfly (1), mounted with the ability to rotate inside the body (2) from an open position revealing the passage to a closed position covering said passage, and a seal (3) arranged inside a housing which is delimited by the seat and by a face, opposite the seat in the closed position, of the butterfly, the seat and the face converging towards the inside in the axial direction. The seal (3) moves freely in the housing.

The invention claimed is: 
     
       1. A valve comprising:
 a body defining, by means of an annular internal seat, an internal area forming a passage with an axial direction, 
 a centred butterfly mounted with the ability to rotate inside the body from an open position revealing the passage to a closed position covering said passage, 
 a seal arranged inside a housing which is delimited by the seat and by a face, opposite the seat in the closed position, of the butterfly, the seat and the face converging towards each other in a direction of a rotational axis of the centred butterfly, characterized in that, in the closed position, the seal is free to move in its entirety in all directions inside the housing. 
 
     
     
       2. The valve according to  claim 1 , characterized by a means of preventing the seal leaving the housing simply by moving without being deformed. 
     
     
       3. The valve according to  claim 2 , characterized in that said means is an anti-ejection ring. 
     
     
       4. The valve according to  claim 2 , characterized in that said means is a circumferential groove inside the body. 
     
     
       5. The valve according to  claim 1 , characterized in that a housing dimension in the axial direction is larger than a seal dimension in the axial direction by between 1 and 50% of the seal dimension in the axial direction. 
     
     
       6. The valve according to  claim 5 , characterized in that the housing dimension in the axial direction is at a position on the housing that is furthest from the inside than any other position on the housing. 
     
     
       7. The valve according to  claim 1 , characterized in that a housing dimension in a radial direction perpendicular to the axial direction is larger than a seal dimension in the radial direction by between 1 and 50% of the seal dimension in the radial direction. 
     
     
       8. The valve according to  claim 7 , characterized in that the housing dimension in the radial direction is at a position on the housing that is furthest from the inside than any other position on the housing. 
     
     
       9. The valve according to  claim 1 , characterized in that the seal is an O-ring or lip seal. 
     
     
       10. The valve according to  claim 9 , wherein the seal is energized by an elastic core. 
     
     
       11. The valve according to  claim 1 , characterized in that said valve is furnished with two seals on either side of the butterfly in the closed position.